I have a 2000 licoln LS. every so often wile driving the drive indecater(D5) on the dash will change to E. Car has 142000 miles and the eng. lights on.

2002 Lincoln LS Owner Guide 2nd Printing d5 is your drive gear with overdrive the d4 used for loads, towing, pg 164 and 165 explains

In your Lincoln LS, you will have 3 transmission options to choose from. The first is the SelectShift, which operates similar to a manual transmission but without the clutch. The other 2 are the D4 and D5 options that you are referring to. The number after the D is really a reference to how many gears it will shift through. D4 = 4 gears, D5 = 5 gears. All that being said, it really should operate closer to a 4 gear transmission with an overdrive gear when the car is in D5. Think of it like the "drive" and "overdrive" in other cars. I have heard that to maximize fuel economy, use D5 for highway driving and D4 for city driving.

try to change the park plug first then if not checked the pcv valve if clogged

The service indicator works on how you drive the car rather than on mileage

D is for Drive. 5 and 4 is for the gear. the higher the gear the better fuel economy.

E=error,the gear indicator has lost a signal from the transmission as to what gear it is in.
when you cycle the key and its ok,means it is a soft code and not a hard code.you need to have it checked on a computer before you cycle the key,

if u drive for short distance chek your charging system if ok replace cluster

Have seen alot of wheel speed sensor problems on this car. May have damaged wheel speed sensor ring or debris interupting signal when wheels were installed. If you can I need to know what code was in ABS module to point you in the right direction. Thanks!

transmission shift throttle adjustment under the car in the middle above the drive shaft there is a heat shield remove it and u will see the shift cable

mileage on vehicle?...could be clogged catalytic converter